ITSL Coal Liquid as a Combustion Turbine Fuel

The combustion characteristics of low-hydrogen-content distillate fuels produced from coal differ from those of conventional petroleum distillates. The differences include: increased flame emissivity which contributes to higher combustor liner temperature, and increased fuel-bound nitrogen which contributes to higher NO_x emission. This paper presents the results of a laboratory test program to evaluate the emissions and combustor performance characteristics when burning the ITSL heavy distillate coal-derived liquid (CDL), and thus determine its acceptability and suitability as a utility combustion turbine fuel. The chemical and physical properties characterizing the test fuel were determined. The trace metals, such as sodium, potassium, vanadium, etc., are low and within concentrations presently allowable in fuel oil specifications. The burner performance factors on the CDL fuel did not differ significantly from those of the baseline No. 2 fuel. Evaluation and comparison of combustor wall temperatures when burning ITSL showed the increase in wall temperature (above No. 2 fuel) to be consistent with expectations. Emissions were measured over an equivalent load range of 30 to 100 percent engine base load. The increase in the measured NO_x emissions with increasing combustor temperature rise (load) was observed. The usual reduction of NO_x with water injection into the combustor was also observed. Other emissions, such as CO, UHC, O₂, and CO₂ for the ITSL fuel generally followed the usual characteristics with load. The ITSL Heavy distillate was found to be an acceptable coal-derived liquid fuel for combustion turbine applications.